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decoder_reader.go
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/
decoder_reader.go
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// Copyright 2017-21 the original author or authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package pbf
import (
"bytes"
"encoding/binary"
"io"
"google.golang.org/protobuf/proto"
"m4o.io/pbf/protobuf"
)
type blobReader struct {
r io.Reader
}
func newBlobReader(r io.Reader) blobReader {
return blobReader{r: r}
}
// readBlobHeader unmarshals a header from an array of protobuf encoded bytes.
// The header is used when decoding blobs into OSM elements.
func (b blobReader) readBlobHeader(buffer *bytes.Buffer) (header *protobuf.BlobHeader, err error) {
var size uint32
err = binary.Read(b.r, binary.BigEndian, &size)
if err != nil {
return nil, err
}
buffer.Reset()
if _, err := io.CopyN(buffer, b.r, int64(size)); err != nil {
return nil, err
}
header = &protobuf.BlobHeader{}
if err := proto.Unmarshal(buffer.Bytes(), header); err != nil {
return nil, err
}
return header, nil
}
// readBlob unmarshals a blob from an array of protobuf encoded bytes. The
// blob still needs to be decoded into OSM elements using decode().
func (b blobReader) readBlob(buffer *bytes.Buffer, header *protobuf.BlobHeader) (*protobuf.Blob, error) {
size := header.GetDatasize()
buffer.Reset()
if _, err := io.CopyN(buffer, b.r, int64(size)); err != nil {
return nil, err
}
blob := &protobuf.Blob{}
if err := proto.Unmarshal(buffer.Bytes(), blob); err != nil {
return nil, err
}
return blob, nil
}